1. Field of the Invention
The present invention relates to a driver bit, and more particularly, to a bit with projections on the bit shank to interlock with surfaces of the bit holder to reduce the tendency of the bit to slip out of the bit holder. The present invention also relates to a driver tool, and more particularly, to a driver tool that engages various sockets, the driver having projections on the portion thereof that engages a socket, to interlock with the inner surface of the socket to reduce the tendency of the socket to slip off of the driver.
2. Brief Description of Related Art
Tools having removable bits for engaging and driving various fasteners into a work-piece are known. For example, screwdrivers that have interchangeable, removable bits are known. The prior art is dominated with hexagonal driver bits modified with various fasteners to be used in an appropriately modified bit holder. A clearance is provided between the holder and the driver bit to allow ease of insertion and changing of the bit. Various retention methods that rely on interference fits e.g., rubber o-rings, etc., or mechanical locking mechanism (snap rings, etc.), or magnetic attraction are currently used, but are subject to failure due to breakage, loss of parts, magnetic weakening and wear to the inner surfaces of the bit holder.
U.S. Pat. No. 4,209,182 issued to Sheldon discloses an axially movable sleeve retained in the bore of a portable rotary housing, disposed around a spindle to hold captive a ball key which releasably retains a screwdriver bit. The sleeve is retained in the housing by a spring retainer (or the like), whereby the bit (and the retainer) may be removed and replaced by axial displacement of the sleeve. Two patents from Habermehl et al., U.S. Pat. Nos. 5,351,586 and 5,531,143 disclose a screwdriver with a replacement bit assembly, where the bit is secured to a mandrel that is axially slidable in a socket in the end of the mandrel. These patents teach a split-ring on the bit which serves to retain the bit in the socket.
Driver tools are also known in the art. For example, socket drivers are known to employ a displaceable ball bearing retaining mechanism to hold a plurality of sockets on the driver. However, such mechanism are also prone to wear, which can render the retaining mechanism ineffective. Similar driving devices having both male driving portions (e.g., hex keys, Allen.TM. wrenches, etc.) and female driving portions (e.g., socket wrenches, etc.) are known, but each suffer from the aforementioned problems associated with screwdriver bits.
Thus, although the prior art discloses various bit and driver retention mechanisms, none of the prior art provides a bit retention mechanism that can be used with standardized holders. Also, prior art devices suffer because there is the need to create complicated retention mechanisms and holders that can break, wear, or are expensive to manufacture.